const s = 'abciiidef'
const k = 3
var maxVowels = function(s, k) {
    let max = 0//最大元音数
    let count = 0//当前窗口元音数
    for (let i = 0; i < s.length; i++) {
        if (i >= k) {
            if ('aeiou'.includes(s[i - k])) {
                count--
            }
        }
        if ('aeiou'.includes(s[i])) {
            count++
        }
        max = Math.max(max, count)
    }
    return max
};